Getting laid

[Chaosboye]

Now, my English teacher once told me that in the past tense, lay is used when not connected to an object, laid with an object. However, we say "I got laid." laid is not connected to an object here, like in "I laid my back on the grass", so I thought it was incorrect. Am I right or wrong? Either way, could someone explain why we say gettin laid instead of gettin lay?

[gmalivuk]

we say "I got laid." laid is not connected to an object here

Yes it is. "Get laid" is a passive construction, like "get paid". If I say that Jake got paid yesterday, then it means someone paid Jake (i.e. Jake is the object of that action).

Of course, there's also the fact that "get laid" is an idiom that doesn't use quite the usual sense of "lay", so we shouldn't expect it to follow all the same rules as in formal academic English. (After all, would you say someone got laid in a school paper or business letter?)

[ZLVT]

When the verb is intransitive (e.g I lie on the bed) it goes lie; lay; have lain. When it's transitive (I lay the book down) it goes lay; laid; have laid (remember it goes like say said said). The verb lie is very similar to lay and people often confuse the two but they are two distinct verbs.

the problem is that the rule would be better stated saying that the conjugation pattern is lay laid laid if the verb has a patient. since in english passive constructs reverse subject and object.
In this case you use lay (laid) because as gmalivuk said get laid is passive and thus uses the past participle not past tense. Get is often used in passives as a synonym for be or become, try exchanging them to see whether it still works.
In passive setntences, the object of the active form (patient) now becomes the subject. This means passive constructs can only be used with transitive verbs. so when your teacher said it has to have an object, from the active verb standpoint "I got laid" or rather "I was laid (by her)" has an object, namely "I" -> "She laid me (down on the bed)". But when you don't want to specify the agent you turn the patient into a subject and make everything passive.

*agent: nouns doing the action; patient: noun suffering the action